Control system for heating devices



4 Sheets-Sheet l INVENTOR,

ATTORNEY.

CONTROL SYSTEM FDR HEATING DEVICES Filed July 25, 1945 fwm A Mon 5 BY fizz A Z5 Oct. 12, 1943.

CONTROL SYSTEM FOR HEATING DEVICES E. A. JONES 2,331,476

Filed July 25, 1940 4 Shets-Sheet 2 0 OPEN/NC M070]? a 0 Vs" K Mi A 1 8 ClOS/fi/G //V-$'l/ZAT/O/V MOTOR.

P'fll/Cf/O/V 10 I j 3 GEAR/1V6 Z 18 a 15 a 5 4! 20 15 b INVENTOR iW/m/ 1% Mal 5 'ITORNEY.

CONTROL SYSTEM FOR HEATING DEVICES Filed July 25, 1940 4 Sheets-Sheet s INVENTOR. [mum/A z/A/is 22 a X ATTORNEY.

12, 1943. l E. A, JONES 2,331,476

CONTROL SYSTEM FOR HEATING DEVICES Filed July 25, 1940 4 Shee ts-Sheet 4 Y fflW/A/ .6 Mon/5 Patented a. 12, .1943.

UNITED STATES PATENT OFFICE,

. assign s v coN'moL sYsrE-M'Foit nm'rme DEVICES Edwin A. Jones, Shorewood, Wis. Application July 25, 1940, Serial No. 341, 71

24 Claims.

This invention relates to control means and to a system of control for heating devices.

In order to simplify the description, the invention will be described as applicable to the heating of a building or house, for example, although it is to be distinctly understood that the invention is also applicable to the control of industrial installations in processes where accurate control of heat is involved.

Objects of this invention are to provide a system of control for heat exchange means which will prevent too rapid an increase or decrease in temperature of the heating device while still retaining the possibility of quick response of the heating device when needed.

In greater, detail, further objects are to provide a control means and a system of control for heating devices, for example furnaces, which is so made thatthe furnace is allowed to heat up in a step by step manner, one of the control deconstructed that ordinarily it will work in conjunction with the step by step, thermal time demeans has, during this interval, no tontrol on the reversely acting motor means.

This'invention has for its further object, the provision of reversely acting motor, means in asystem of control which may operate a modulating pilot valve to thereby modulate a main modulating regulator valve, such latter being so com I nected in the system that" it first allows one invices being placed at a point where it quickly responds to the heat from the furnace or heating medium, in which motor means are provided for reducing the flame at the burner which is caused to wait a predetermined period of time to ascertain if a sufficient amount of heat has been furnished the house, and is thereafter allowed to.

function to allow a greater supply of fuel to the burner in the event suflicient heat has not been furnished the house, and thus in a step by step manner feels out, so to speak, the demand for heat, the control means being so constructed that it operates independently of the actual temperature of its thermally responsive parts but operates primarily'in response to a sudden increase duction gearing to. control either an auxiliary modulating valve, which in turn controls 'a main modulating valve, or which directly controls a modulating valve to thereby modulate either the flow of one ingredient of a combustible mixture or the flow of a heating means, or the relative flow of heating and cooling means, the reversely a cting motor means being in turn under the control of a main thermostat and a thermally responsive time, delay means,which latter will cause a'ste'p by step action of the motor .means in either direction.

Further objects are to provide a control device and a system of control in which the reversely acting motor means are provided which are in turn controlled by a thermally actuated time delay device for'causing a step by step action in either .direction of the motor means, and which is also controlled by a room or other main thermostat, theroom or, main thermostat beingso the accompanying drawings, in which:

Figure 1 shows the control apparatus applied to a furnace, such .view having parts broken :vention showing the system as gredient of a combustible mixture to come on at regulated pressure and thereafter modulates such ingredient in accordance with the action of the reversely acting motor means, such rever sely acting motor means being also so arranged that it can directly control a modulating valve to thereby directly modulate the supply of a heating medium, or which may directly modulate a valve construction which will proportion the amount of hot and cold air supplied a building or other space.

In still greater detail, further objects are to provide a reversely acting motor means which is controlled from a main thermostat, such asa room thermostat, and from a step by step thermally actuated time delay device, such reversely acting motor means operating a modulating;

valve in a graduated manner to provide for a floating operation of the valve, either towards open or towards closed-position, limit means being provided to arrest the operation of the motor means at the limit of either direction of oper-' ation.

Embodiments of the invention are shown away.

Figure 2 is a view showing in section a modu lating regulator and a fluidactuated time delay device,

Figure 3 is a diagrammatic view, showing the reversely acting motor means, the step by step thermally. actuated time delay means, the room thermostat, and the on and oil electric valve, together with a wiring diagram of the'system. Figure 4 is a sectional detail of the auxiliary throttling valve which is actuated by the re-' versely acting motor means.

Figure 5 is a view partly in section' of the step by step thermally actuated timedelay means.

Figure 6 is a sectional view approximately Ion theline66ofFigure5. Figure 7 is a view'ofa further formof the inrect control yf a heating medium. a

Figure 8 is a diagrammatic view showing the applied to the disystem as applied to the control of a mixture of.

thermostat controls two reversely operating electric motors, one of which may be called an opening motor-and 'the other a closing motor indicated generally at M1 and M2;

These reversely operating motors may be of any suitable type but are preferably of the selfstarting synchronous type. They are rigidly connected by a common shaft l which, through a high reduction gearingindicated generally at 2, drives the cam shaft 3. A cam 4 is rigidly carried by the shaft 2 and is slowly driven in one or the other direction, depending on whether the opening motor M1 or the closing motor M2 is in operation. These motors are selectively controlled by theqnain thermostat T1. However, the 'controlis interrupted periodically, under certain conditions which will hereinafter be described, by a thermal time delay means indicated generally at T2.

This thermal time delay means is located. at

a point where it is quickly affected by the heat;

from the burner for instance, or by a part of the circulating medium, or at all events,-at a point where it responds very quickly for any increase or decrease of temperature, whereas the main thermostat T1 is located at the point or in the space to be heated and may be relatively remote from the burner or other heating medium.

The purpose of this relation of the parts is to prevent too rapid a heating or too rapid a cooling and to cause the apparatus to operate in a step by step manner.

The cam 4 in the form shown in Figure 3 controls anauxiliary throttling valve indicated generally at 5 and this throttling valve, as will appear hereinafter, controls a modulating regulator which in turn controls the flow of fuel to a burnerfor the formshown in Figures 1 and 3.

provided with adjustable upper and lower stationary contacts l2 and I3. These stationary contacts 12 and I3 cooperate respectively .with the limit switches 14 and I5 which may be spring arms which areadapted to be operated from the cam follower lever l5, such last mentioned lever cooperating with the cam 4 and being urged downwardly by means of the spring I! and pivoted, for example, upon the knife edge l8.

' This camfollower lever I6 is provided with an adjustable member l9 which may bear upon the face of the cam. It is also provided adjacent its outer end with a rod which may be of insulating material and which operates the upper and lower limit switches l4 and I5. The upper. limit switch I4 controls the opening motor and the lower limit switch l5 controls the closing motor, and the on and off valve 6, it being noted that the on and off valve is an ordinary type of electric on and oil valve.

A simple form of motor which is eminently suited to this system is the self-starting type of synchronous motor and such has been indicated for the opening and closing motors M1 and M2. The opening motor comprises the armature 2| and the field 22 and the closing motor comprises the armature 23 and the field 24.

Tracing the circuit from the lower terminal of the step-down transformer 8, it is apparent that The modulating regulator may control either ingredient of the combustible mixture.- It. will be described as controlling the supply offuel such as gas, though it obviously could control the.

flow of air; in which case it would be used in conjunction with the ordinary zero pressure regulator, which in turn would control the flow of gas. 5

A main on and off valve indicated generally at 5 is provided for the fuel supplyand is located between the modulating regulator indicated generally at R in Figure 1 and the burner means 1. A smallstep-down transformer 8, see Figure 3, provides the electrical energy for operating the apparatus. It is to be noted also from Figure 3 that a limit control, such as a thermostat 9 which may be located in the bonnet ofthe furnace or wherever desired, is provided in the system and operates in the usual manner of such limit controls.

Referring in detail to Figure 3, it will be seen that-the transformer 8 has one side of the secondary connected by means of theconductor III with a stationary contact member H which is such lower terminal, inthe position of the parts shown in the drawing, is connected through the conductor ID to the contact member II, and from the upper limit switch I4 to the field 22.

From this point the connection extendsto the spring arin or relatively stationary contact arm 25 of the thermal time delay device or step by step device. The relatively stationary contact arm 25, which will hereinafter be referred to as one of the, stationary contact arms of the time delay step by' step device, is provided with a contact which is normally in engagement with the contacting portion 26. This contacting portion is connected to the terminal 21 and from this point to the contact 28 of the main tlfermo-' stat T1.

One side of the field 24 of the closing motor is connected to the.lower limit switch i5-and the other side of the field-is connected to the spring arm or relatively stationary? contact 29 of the device T2.

This relatively stationary contact arm; which will hereinafter be referred to as a stationary contact of the device T2, is provided with a contact at its outer or' free end which normally engages the conducting portion 30 of the device T2. This conducting portion is connected to the terminal 3| and from thence to the contact 32 of the main thermostat T1. -It is to be noted from Figure 3, that the lower contact 33 below the contact 28 of the main thermostat T1 and the lower contact 34 below the contact 32 are respectively connected'to one side of the fields 22 and 24 of the opening and closing motors for a purpose hereinafter toappear. These contacts 33 and 34 may be omitted when not deemed necessary. I,

The bi-met'allic strip 35 of the main thermostat T1 is connected to the other side of the secondary of the transformer 8. Such other sideof the secondary of the transformer is also connected through the limit control 9 to one terminal of the solenoid indicated generally at 36 of the electric on and .ofl valve 6. The other terlower limit switch I5.

Before describing the operation of the circuit and the associated parts shown in Figure 3, it is to be noted, as will hereinafter appear, that the thermally actuated time delay device or step by step device T2 is provided with an outer shell 31 and an inner rod 38 which are either of exactly the same materialor else are of materials having substantially the same coefilclent of expansion. The tube 31 is rigidly carried by the body portion 39 of its structure while the rod 38 extends through this stationary portion and bears against 3 nary type of hot air furnace merely for the sake of one illustration of its applicability, it being understood that the device can be applied to other types of heating equipment, whether of the a part of the rocking lever 40 of the step by step device, such portion 48 being of insulating material and being pivoted as indicated at 4|, all as will appear in greater detail when the actual structure of this device as shown in Figures 5 and 6 is described.

It is apparent, therefore, that whenthis device is located at a place where it responds very quickly to any change in temperature due to the operation of the'burner for example, as-for instance when it is installed in the smoke pipe as shown in Figure 1, that after the burner has operateda short time, the outer tube 31 willrod 38 is drawn to the left as viewed in Figure 3, and the connection between the members 26 and Y 25 is interrupted and consequently the circuit of the opening motor is interrupted. After an interval of time, however, the expansion of the .ing 5' of Figure 1.

tube 31 and the parts of the dev ce T2 will then assume their normal position as s own in Figure 3, thus allowing the opening motor to continue 7 its opening operation.

On the other hand, if the temperature in the flue, for instance, should drop too rapidly, it, is apparent that the contraction-of the outer sleeve 31 will be faster than the contraction of the inner rod 38, with the consequence that the member of the-device T2 will be moved to the right; thus opening the circuit of the closing motor. However, after an interval of time, the contraction of the outer tube 31 and the rod 38 will be the same and the parts will assume their normal position as 'shown in Figure 3, thus re,- establishi'ng the circuit of the closing motor.

From the description thus far given, it is apparent that the main thermostat T1 selectively controls the operation of the opening and closing motors and that this control of these motors from the main thermostat is periodically interruptedwhen'tooquick a change intemperature immediately adjacent the burner, for instance, occurs, and that thecontrol is reestablished after predetermined interval of time.

It. is to be noted also that if the main thermostat T1 should move to either the left or the right beyond the point where the contacts 28/or 32 are engaged, that it will engage the station-- ary contacts 33 or 34 respectively. When so engaged, it is apparent that the step by step device" that'the arms carrying the corresponding contacts for engagement therewith are yielding spring arms.

Figure 1 shows "the device appliedto an ordithis change intemperature has persisted for a has been indicated by thereference character 4| and has been shown as provided with a smoke pipe 42 within which the time delay thermostatically operated step by step device T2 is installed, the contact portions of the device being located externally of the smoke pipe and the thermally responsive members, namely, the tube 31 and rod 38, being located within the smoke pipe. The limit control 9 is located in the bonnet of the furnace inthe usual manner.. The furnace has been illustrated as a gas fired iumace in which the burner means 1 are provided with the pilot lights 43 and in which the gas supply-pipe is indicated by the reference character 44. This gas supply pipe passes first to the modulating regulator R and then to the on and off valve 6, and from there passes to the burner means 1.

The opening and closing motors M1 and M2 are indicated generally in Figure '1, the auxiliary throttling valve 5,being located within the hous- The pipes leading to the auxiliary throttling valve 5 are indicated in Figures 1, 3 and 4 by the reference characters 45 and 46. I v

The auxiliary throttling valve 5 is'shown in detail in Figure .4 and it will be seen that it comprises the valve seat portion 41 and the cooperating valve 48. The valve 48 is carried by a stem .49 and is spring urged towards closed position by means of th spring 50. The stem 49 extends loosely thr ugh an opening in the cam follower or lever l3 and is provided with a transversely extending pin 5| located on the upper side and adapted to be engaged .by the lever l6 to thus raise the valve towards open position ment of the member l9, determines the points against the action of the spring 50.

It is obvious that the adjustment of the member l9 provides any desired amount of lost motion, and it is also clear that the adjustment of the contacts l2 and I 3, together wlththe adjustat which the opening and closing motors will have their circuits opened and closed.

Themodulating regulator R. and a fluid actuated time delay'means indicated generally at D in Figures 1 and 2, are described in detail in ber 53 and an outletvchamber 54. This body portion carries the lower and upper casing members 55 and 58 between which a diaphragm 51 is positioned. This diaphragm is spring biased downwardly by, means of the spring 58 whose degree of compression may be adjusted, as is obvious from an inspection of Figure 2.

The diaphragm 51 divides the upper casing portionoL, the structure into an upper chamber 59, which is freely vented to the air as indi cated, and a lower chamber 58. The lower chamber communicates with the inlet chamber 53 of the body portion by means of a regulatable pressure inlet bleed 8i.

A regulatable by-pass or flame bypass 62 is provided between the inlet chamber .53 and thekoutlet chamber of the body porwardly.

tion so thatwhen the modulating'regulator valve 63 fully engages its seat portion 64, there nevertheless will be minimum flame by-pass provided by the structure. A small freely flexible sealing diaphragm 65 seals the inlet chamber 53 from the chamber 80.

The bottom chamber 60 is provided with the pipe 45 previously described which constitutes a bleed line pipe and extends to the auxiliary throttling valve indicated generally at 5. The pipe 46 leads from the auxiliary throttling valve 5 to. the outlet chamber 54 of the modulating regulator. -It is apparent, therefore, that if the time'delay valve D hereinafter described in greater detail is in the closed position as shown in Figure 2, that pressure will build up below the diaphragm 51 in the chamber 58, being supplied through the small passageway 5| from the high pressure side of the mains.

As the throttling valve 5 opens up, this pressure is relieved to a greater and greater extent as the pressure gas in the chamber 60, see Fig ure 2, is discharged to ,the outlet chamber 54 of the modulating regulator and thus the diaphragm '51, which is spring pressed downwardly, descends andcmoves the valve 63 downwardly, thus increasing the opening through the modulating regulator and allowing an increase in flow of fuel to occur. Obviously when the auxiliary throttling valve 5 closes, the modulating regulator will also close as the bleed from the chamber 60 is now cut oil? and pressure builds up and closes the mo ulating regulator. However, a minimum flam supply is by-passed through the passage 82.

The'fiuid actuated time delay means D con- "sists of a casing having. the upper and lower casing members 66 and 81 between which a diaphragm 68 is mounted The diaphragm is freely flexible and is weighted so that it is biased down- It carries asmall needle valveor cut off valve 69 which is adapted to cut oil communication between the pipes and II when the pressure above the diaphragm 58 is relieved, as shown in Figure 2, the pressure fluid above the diaphragm 68 freely passing from the pipe II I -to the pipe 46 and from there to the outlet chamber 54 of the modulating regulator. This the position of the parts when the main on and oil valve 6 is open and the modulating regulator is.

in its open position.

The pipe 10 communicates with the pipe 45 and it will be noted that the fluid actuated time delay means D constitutes a by-pass around the auxiliary throttling valve 5, as is apparent from an inspection of Figures 1, 2 and-4.

When the apparatus is in operation, that is to say, when-the burners are being supplied with fuel, the time delay means D has its diaphragm 68 in its uppermost position as shown in Figure 2.

A pipes and I I now directly connect the bleed line 45 with 'the exhaust pipe 46 leading to the outlet chamber 54 of the modulating regulator. The.

modulating regulator, however, moves it valve 63 events, the time of closing of thervalve $9 is predetermined. When the valve 59 is in open posi- It is apparent that when the on and off valve 5,

tion, it is to be understood that a freeband substantially unrestricted passage is provided from the chamber 50 below the diaphragm 51 of the modulating regulator R to the outlet chamber 54 of such modulating regulator, andin view of the i act that the main on and off valve 8 is now open, it is apparent that the pressure uid in the chamber 68 is freely vented to the discharge side of the modulating regulator and consequently the modulating regulator moves to open position whether or not the auxiliary throttling valve 5, see Figures 1 and 4, is open or closed. Thus a certain time interval is allowed whereby a full flow of fuel to the burners is provided so as to insure proper ignition of the fuel at the burners. Thereafter when the fluid actuated time delay device D closes and cuts off direct communication between the chamber 60 of the modulating regulator and its outlet chamber 54, the auxiliary throttling valve 5 assumes control and the modulating regulator moves towards'modulating position, depending on the setting then obtaining for the auxiliary throttling valve 5.

The thermally actuated time delay step by step device T2 is shown in detail in Figure 5. The outer tube 31 and the inner rod 38 may be both formed of copper or any other suitable material having either the same or substantially the same justable slide to open or close more or less of the apertures, as disclosed in' greater detail in my copending application Serial No. 340,452, filed June 14, 1940, for Control means and system of control-for heating devices. The time delay interval is determined by the relative tim it takes to raise or lower the outer tube 31 and the-inner rod 38 to approximately the same temperature. This also may be determinedby the relative mass of the two members.

The rod 38 is adjustably mounted as byscrewing its end into a fitting 12' rigid with the outerend of the tube 31, a suitable lock nut I3 bein provided for locking it irf its adjusted position. The tube 31 is brazed or otherwise rigidly secured to the body portion or relatively fixed portion 39 which may be continued to forma. casing member -39' within which the contact members 25, 26, 29 v and 30 previously described are ,housed, a suitable cover plate 14, see Figure 6, being provided for thecasing.

The rod 38 is provided with a reduced exten s ion 15,- see Figure 5, which sockets within a rounded socket portion formed in the insulatin body or lever 48 of the rocking portion of the device. The contacts adjacent such socket portion are cut away as shown in Figure 5, so that the rod is insulated from any live portion of the apparatus. The normal position of the parts is shown in Figure 5 where the tube 31 and rod 38 are at substantially the same temperature. The

7 2,331,476 operation of this apparatus has been previously.

described and it is to be borne in mind that either the opening or closing motor circuit is opened or closed by this device when the tube 31 is hotter ,than the rod 88, or when the tube 31 is cooler than the rod 88 respectively.

. be by way of the passage 62, see Figure 2. The

The spring arms or contact arms 25 and 29, see

Figure 5, tend to follow the rocking lever, 40 and its contact members 26 and 30, as such rocking lever is moved. To limit or predetermine the agunt of follow through of these contact memb rs 25 and 29, adjustable mean are provided. This adjustable means may consist of a pair .of levers 18 and 11 which are pivoted intermediate their ends. upon the insulating base portion 18 of the member T2.

The levers I8 and I1 carry at their free ends or lower ends as shown in Figure 5, outwardly projecting pins I9 and 80,respe'ctively which are adapted to engage downwardly turned lips 8| and respectively secured to the spring'arms and The levers I6 and TI are forged and engage eccentrically located pins 83 and 84 carried respectively by adjustable, revolubly mounted mem-. bers 85 and 86. It is obvious that when the pins 19 and 88 are moved outwardly, that the follow through of the spring contact members 25 and 29 is more greatly limited than if the pins I9 and 80 are moved inwardly towards each other.

Referring to Figure -3, it will now be understood how'the individual elements of this system function. Their relative or correlated functioning will now be described with reference to Figure 3. The position of the main thermostat T1, for example the room thermostat as shown in Figure 3, is its normal position when the room is' at the desired temperature. A slight decrease in temperature of the room causes the thermostat to engage thestationary contact 28 and this closes the circuit of the opening motor through the step by step member T: as previously described; This opening motor then operates in the direction indicated and rotates the cam 4 so as to raise the lever l8. This operation continues until the limit switch l5 closes, at which time the circuit of the electric ,pendently of the room thermostat T1 or of the member- Ts. when the main on and off valve 8 opens; see Figures 1 and 2, it is apparent that the modulating regulator will move to fully open positionas previously described, as the chamber 80 of the modulating regulator," see-Figure 2, is directly connected to the outlet chamber 5| of the modulating regulator and consequently the valve 8 will be closed indeadjustment of the parts in Figure 3, particu-v larly of the member I9 and the contact l3, may be so made that the auxiliary tluottling valve I5 is partly open at the time that the main on and on valve is opened, in which case the modulating regulator will also move to partly open position instead of fully closed position after the modulating regulator has first moved to fully open position as previously described.

The opening motor slowly drives the cam ,4 to more fully open the auxiliary throttling valve 5 and the modulating regulator. However, the thermally actuated time delay means or step by step means T2 comes into play. as it is heated by the gases in the flue pipe and consequently will open the opening motorlcircuit until the temper-' ature of the rod 38 approaches that of the tube 31, and thu a step by step opening of the auxiliary throttling valve and modulating regulator nished and thereafter the step by step device F1:

stops further increase in the amount of fuel supplied and maintains the fuel supply at the level at which it stopped. If this is suflicient, nothing further happens, but if it is either insuificient or more than required, the step by step device T2 will, after a period of time, reconnect the openpressure fluid in such chamber 80 isimmediately exhausted. The modulating regulator when in fully open position supplies the fuel at predeter-.

mined regulated pressure. y

The time delay device D slowly moves to closed positionand after an interval of time, cuts 011 this by-pass from the chamber 89 to the chamber" of the modulating regulator. Thereafter the modulating regulator is under the control or the auxiliary throttling valve 5 and assumes a position corresponding to that of the auxiliary throttling valve I shown in Figure 3 may be such that the aukiliary throttling valve 5 has not yet been opened and if this is the case, only a minimum flow may be permitted through the-modulating-regulator after the initial full flowhas occurred as the modulating regulator will now move back to closed posi- 5. The adjustment of the parts,

only communication from the inlet I vice would interrupt ing motor in circuit and adjustthe .fuel supply On the other hand, if the'closing motor had been in operation and had been causing a gradual closing of the modulating regulator, it is apparent that the step by step dethe circuit of the closing motor at periodic intervals to prevent toorapid Y a cooling. r

The invention may; take other forms. For instance as shown in Figure 7, the invention is shown as applied to a system of control in which the step by step or thermal time delay means is actuated by the return iiow of a heating medium, which, for instance, may be steam or hot water. 'For example, is supplied from the-supply pipe 81 to a modulating valve or throttling valve 88.

This throttling valve is operated in reverse directions by the opening and closing motors in ex actly the same way ing motors drive the shaft 3; and obviously it may be ofany form desired provided, however, that the opening motor will open the valve and the closing motor close the valve through'some form of reduction gearing to have a relatively slow opening anda relatively slow closing.-

This motor means is indicated generally by the reference character 88' and may correspond to that shown in Figure 3. Under these conditions it is not necessary to have an on and of! valve as previously described and'indicated generally at 8 in Figure 3, for all that is necessary is to appropriately.

throttle .the flow. of the heating medium to a reater or less'extent or to out and this is readily mplished by'the'opening and closing motor me The electrical connectionsare identically the if hotwater is employed, it r that the opening and clos-- it oi! completelyheretofore described; I

same as those shown in Figure 3, with the exception, as stated, that there is'no on and ofi main valve corresponding to the valve 6 of Figure 3 and that there is no limit control 9 associated therewith. The. heating medium passes from the throttling valve or regulating valve 88 to the pipe line 88 and from there passesto one or more radiators 9|.

cut off valve as indicated if desired, or these inanual valves-may be omitted. The return pipe for the heating medium is indicated by the reference character 92 and the step by step member has its thermally responsive portion located within this return pipe as indicated in Figure 7.

The operation of the system shown in Figure '7 is believed to be apparent from the previous description of Figure 3, except for the on and off valve and except for thefact that there is no auxiliary throttling valve corresponding to the valve of Figure 3. Instead, the throttling valve is the main valve 88 which controls the flow of heating medium directly.

In the system shown in Figure '7 it is apparent that when thethermostat Tl, corresponding identically, to that shown in Figure 3, calls for more heat, that the opening motor will start opening the valve 88 and thereafter the step by step or thermal time delay means T2 will function to temporarily arrest the operation of the opening motor. Further operation of the opening motor will then stop. If the flow of the heating medium is sufficient, nothing further happens, but the throttling valve 88 or regulating valve will remain in its adjusted position.

On the other hand, if there is an insufficient flow of heating medium, the room thermostat Tl will remain in the position where it calls a for more heat. For example, it will he to the left as viewed in Figure 3. Under these conditions when the step by step member T2 again closes the opening motor circuit, after an interval of time as previously described, the regulating or throttling valve 88 will open farther and thereafter the operation of the opening motor will be arrested by the functioning of the step by step or thermal time delay means T2.

This cycle will continue until either the full opening position of the regulating or throttling valve 88 has been obtained, at which time the corresponding limit switch will open, or until the room thermostat T1 moves to open position due to the temperature of the room having reached the desired temperature for which the device is set.

The reverse action is, of course, apparent from the previous description, for if the room thermostat moves to the right as viewed in Figure 3. it is apparent that the closing motor will function and the regulating or throttling valve 88 will start to close but will be arrested periodically by the functioning of the device T2, all as previously described.

This invention lends itself readily to the correct relative proportioning of hot and cold air which may be supplied a building in certain types of heating and ventilating installations. Under these conditions, the shaft 3 'is provided with a crank 93, see Figure 8, the opening and closing motor mechanism being indicated generally by the reference character 94. This crank is connected by means of the connecting rod 93 with a plurality of butterfly valves or vanes 95 controlling the supply of hot air, and with a plu- Each' radiator may be provided with an individual manually operable rality of butterfly valves. or vanes 86 controlling the supply of cold air.

These valves or shutters are so'arranged that they work-in opposite directions so that motion 'of the shaft 3 in one direction will tend to cut ofi the supply of hot air and increase the supply of cold air, and the reverse direction will cause the valves to increase the supply of hot air and decrease the supply of cold air; The room thermostat is indicated at T1 and functions in exactly the same manner as that previously described and the step by step member or thermal time delay means is indicated at T2 and functions in exactly the same manner as previously described. Its thermally sensitive portion is located in the mixed air supply pipe-91 at a point some distance from the converging portion 98 so that adequate mixing of the hot and cold air supplied wilrl have occurred prior to the arrival of the mixed air at the step by step member T2. The hot air supply pipe is indicated by the reference character 98 and the cold air supply pipe by the reference character I 00.

It is apparent that if the room temperature should drop below that for which the device is set, that the opening motor will function to increase the supply of hot air and to decrease the supply of cold air. The opening of the hot air valves and the simultaneous closing ofthe cold air valvestakes place slowly and is arrested, after a suitable interval of time, by the functioning of the step by step thermal time delay means T2 as previously described to thereby avoid overshooting.

On the other hand, if the room thermostat called for a decrease in temperature, it is apparent that the closing motor would function to decrease the supply of hot air and increase the supply of cold air, and that again the thermal time delay or step by step means T2 would function to stop the operation of the closiing motor after an interval of time so that the system functions in a step by step manner to feel out, so to speak, the demand either during an increasing or decreasing temperature cycle. It is to be understood that where the expressions hot air and cold air are used, it is intended that they shall be interpreted to mean air of different temperatures.

It is to be understood, in connection with the invention described in Figures 7 and 8, that the room thermostat or main thermostat T1 is identically like that described in connection with Figure 8 and cooperates with the step by step thermal time delay means T2 in exactly the same manner. Thus, if there is a sudden increase or a sudden decrease of temperature in the room due to abnormal causes, the step by step thermal time delay means will be electrically by-passed by the room thermostat and maximum opening or closing of the motor means will occur.

It will be seen that a novel control means and .a novel system of control for heat exchange deduction of rate of temperature change to' below than limiting, as the invention may be variously embodied and is to b interpreted as claimed.

' of an ingredient of a combustible mixture to said burner means, an auxiliary valve controlling the supply of said ingredient to said burner means, electrical power means for operating said auxiliary valve in both directions, and time delay thermostatic means for causing a step by step action of said auxiliary valve, said time-delay means being disposed to beoperated in response to changes in temperature produced by the burner.

2. In a. control system for heating devices including burner means, a main thermostat responsive to the temperature produced by said burner means, an on and oii valve controlled from said main thermostat ,for controlling the supply of an ingredient of a combustible mixture to said burner means, an auxiliary valve con-' trolling the supply of said ingredient to said burner means, electrical motor means for operating said auxiliary valve in opposite directions,

and thermostatic means acting intermittently upon rapid change in temperature changes'produced by the burner, oper tively connected for causing intermittent operat on of said auxiliary valve to temporarily arrest the increase or decrease of the supply or said one ingredient to said burner means upon a rapid increase or decrease, respectively, of the heat supplied by said burner means.

3. In a control system for heating devices including burner means, a main thermostat 'responsive to the temperature produced by said burner means, a valve for causing modulation of the supply of one ingredient of a combustible mixture to said burner means, electrical motor means for moving said valve towards open and said electrical motor means being controlled by said main thermostat, time delay thermostatic means heated from said burner means for causing intermittent operation of said motor means to thereby cause a temporary cessation of operation of said" electrical motor means upon rapid change of temperature produced by said burner means, a main electrical on and off valv for controlling the supply of the said ingredient tosaid burner means, and a limit switch operated from said motor means for controlling said main on and of! valve.

4. In a control system for a heating device, a

source of supply of a heating medium, amain thermostat responsive to the temperature produced by said heating device, a valve for causing direct modulation of the supply of said heating medium to said heating device, electrical motor means for moving said valve towards open and closed positions, said electrical motor means being controlled by said main'thermostat, and

timedelay thermostatic means operated from"an initial to a second position in response to temperature changes produced in the heating medium' at rates above a predetermined value, and operated back to initial position upon remotor means and second position in response to temperature.

said value, said time-delay thermostatic means being connected to cause a temporary cessation of the operation of said motor means upon rapid change of temperature produced, said time delay thermostatic means being heated from the heating medium which passes through said heating device.

5. In a control system for a heating device, 'a' source of supply of a heating medium, a main thermostat responsive to the temperature produced by said heating device, a valve for causing direct modulation of the supply of said heating medium to said heating device, electrical motor means for moving said valve towards .open and closed positions, said electrical motor .means being controlled by said main thermostat,

low said value, said time-delay thermostatic.

means being connected to cause a temporary cessation of the operation of said motor means upon rapid change of temperature produced, said time delay thermostatic means being more directly heated from said heating medium than said main thermostat.

6. In a system of control a source of hot air andasource of cold air, means for conducting a mixture of the air from the two sources to a space whose temperature is to be controlled, a main thermostat located within said space, valve means for varying the proportion of hot and cold air, electrical motor means for moving said valve means to vary the proportion of said hot and cold air, said electrical motor means being controlled from said main thermostat, and time delay thermostatic means heated by the mixture of the hot and cold air while said hot and cold air is being conducted to the said space, said time delay thermostatic means controlling said motormeans and operated from an initial to a second position in response to temperature changes in the air to which it is subjected at rates above a predetermined value, and operated back to initial position upon reduction ofrate of temperature change to below said value, said time-delay thermostatic means being connected to cause intermittent operation of said motor means upon rapid change of temperature of the air while it is being conducted to the said space. '7. In a system of control a source of hot air and a source of cold air, means for conducting a mixture of the air from the two sources to a spacewhose temperature-is to be,-controlled, a main thermostat located within said space, valve means for varying the proportion of hot and cold air, electrical motor means for moving said valve means to vary the proportion of said hot and cold air, said electrical motor means including two electric motors arranged to rotate in reverse directions, and reduction gearing operatively connecting said motors with said valve means, said electrical motor means being controlled from said main thermostat, and time delay thermostatic means heated by the mixture of the hot and cold 'air while said hot andcold air is being conducted to the said space, said time delay thermostatic means controlling said operated from an initial to a changes in-the air to which it is subjected at 7 rates above, a predetermined value, and operated ture of said medium, time delay thermostatic means responsive to the heat from said heating means more quickly than said main thermostat and including two members-each of which expands on heating and one of which heats up v more, quickly than the other and switch means operated by thediflference inrexpansion of said members, said switch means being operated from a first to a second position upon rapid change of heat applied to the two members, and being operated back to first position upon continued application of heat thereto, valve means controlling the operation of said heating means and including electrical power means for, operating said valve means in a graduated manner, said electrical power means being under the control of said main thermostat and said time delay thermostatic means switch.

9. In a control system for heating devices including heating means for heating a medium, a main thermostat responsive to the temperature of said medium, time delay thermostatic means responsive to the heat from said heating means more quickly than said main thermostat and including two members each of which expands on heating and one of which heats up more quickly than the other and switch means operated by the difierence in expansion of said members, valve means controlling the operation of said heating means and including electrical power means for operating said valve means in a graduated manner, said electrical power means being under the control of said main thermostat and said time delay thermostatic means, said main thermostat having two sets of contacts one of which opens and closes for normal variations in temperature of said medium and the other of which opens and closes for abnormal temperature variations, said last mentioned set of contacts being connected in a circuit which bypasses said time delay thermostatic means.

10. In a'control system for, heating devices includingburner means, a main thermostat responsive to the temperature produced by said burner means, on and off valve means controlled from said thermostat for controlling the supply of an ingredient of a combustible mixture to said burner means, an auxiliary valve controlling the supply of said ingredient to said burner means, means for positively operating said auxiliary valve in both directions, and time delay thermostatic means operatively connected tomixture .to said burner means, means for mov- Gil ing said valve towards open and closed positions, said means being controlled by said main thermostat, and time delay thermostatic means heated from said burner means for causing intermittent operation of said means to thereby cause a temporary cessation of the operation of said means upon rapid change of temperature produced by said burner means, said time delay thermostatic means being more directly heated from said burner means than said main thermostat said time delay means comprising a mechanism moved from first to second position upon initial heat change, and moved'from second to first position upon continued heat change, and in said second position being adapted to stop said burner means as aforesaid.

1,2. In a control system for heating devices in-- cluding heating means for heating a' medium, a main thermostat responsive to the temperature of said medium, a main on and off valve controlled from said main thermostat, time delay thermostatic means responsive to the heat from said heating means more quickly than said main thermostat and including' two members each of which expands on heating and one of which heats up more quickly than the other and switch means operated by the difierence in expansion of said members, said switch means bein operated from a first to a second position upon rapid change of heat applied to the two members, and being operated back to first position upon continued application of heat thereto, valve means controlling the operation of said heating means and including electrical power means for operating said valve means in a graduated manner, said electrical power means being under the control of said main thermostat and said time delay thermostatic means.

13. In a control system for heating devices including heating means for heating a medium, a main thermostat responsive to the temperature of said medium, a main on and off valve controlled from said main thermostat, time delay thermostatic means responsive to the heat from said heating means more quickly than said main thermostat and including two members each of which expands on heating and one of which heats up more quickly than the other and switch 7 means operated by the difference in expansion of said members, said switch means being oper-- ated from a first to a second position upon rapid change of heat applied to the two members, and

being operated back to first position upon continued application of heat thereto, valve means controlling the operation of said heating means and including electrical power means for operating said valve means in a graduated'manner, said electrical power means being under the control of said main thermostat and said time delay thermostatic means, said main thermostat having two sets of contacts one of which opens and closes for normal variations in temperature of said medium and the other of which opens and closes for abnormal temperature variations, said last mentioned set of contacts being connected in a circuit which by-passes said time delay thermostatic means.

14. In a control system for heating devices ineluding burner means, a main thermostat rebustible mixture to the burner means, an

auxiliary valve for contrplling the position of the modulating valve, means for selectively burner means, a valve for causing modulation closed positions, said electrical motor means of said electrical motor means upon rapid change being adapted to return to initial position upon operating said auxiliary valve in both closing and :opening directions, and time delay thermostatic tion upon initial heat change, and moved from second to first position upon. continued heat change, and in said second position being adapted to stop said burner means as aforesaid said auxiliary valve and said modulating valve main-,

taining achieved positions during cessation of the operating means. v

15. In a control systemior heating devices including burner means, a main thermostat responsive to the temperature produced by said of the supply of one ingredient of a combustible mixture to said burner means, electrical motor means for moving said valve towards open and 'closed positions, said electrical motor means being controlled by said main thermostat, and time-delay thermostatic means operated from an initial to a second position in response ,to. temperature changes produced by the burner means at rates above a predetermined value, and operated back to, initial position upon reduction of rate of temperature change to below said value, 'said time-delay means being connected to cause a temporary cessatidn of the operation of said electrical motor meansvupon rapid change of temperature produced by said burner means, said valve maintaining its previously achieved position during temporary cessation of the motor means, and the time-delay thermostatic means being adapted to return to initial position upon reduction of rate of change of said temperature, to return the electrical motor means to control of the main thermostat. 16. In a control system for heating devices including burner-means, a main thermostat responsive to the temperature produced by said burner means, a valve .for causing modulation of the supply of'one ingredient of a combustible mixture to said burner means, electrical motor' means for moving said valve towards open andbeing controlled by said main thermostat, and time-delay thermostatic means operated from an initial to a: second position in response to temperature changes produced by the burner means at rates above a predetermined value, and operated back to initial position upon reduction of rate of temperature change to below said value, said-time-delay :means being connected to cause a temporary cessation of the operation of temperature produced by said burner means,

said valve maintaining its previously achieved position during temporary cessation of themotor means, and the time-delay thermostatic means reduction of rate of change of said temperature,

to return the electrical motor means to controL. of the main thermostat, said time-delay thermostatic means being more direcly heated from said burner means than said main thermostat.

17. In a control system for heating devices including burner means, a main thermostat responsiveto the temperature produced bysaid burner means, a valve for causing modulation of the supply of one ingredient of a combustible 75 mixture to said burner means, electrical motor means for moving said valve towards open and closed positions, said electrical motor means including two electric motors arranged to rotate in reverse directions, and" reduction gearing operatively connecting said motors with said valve, said electrical motor means being controlled by said main thermostat, and time-delay thermostatic means operated from an initial to a second position in response to temperature changes produced by'the burr-er means at rates above a predetermined value, and operated back to initial position upon reduction of.rateof temperature change to below said value, said timedelay means being connected to cause a temporary cessation of the operation of said electrical motor means upon'rapid change of temperature produced by said burner means, said valvemaintaining its previously achieved position during temporary cessation of the motor means, and the time-delay thermostatic means being adapted to return' to initial position upon reduction of rate of change of said temperature, to return the electrical motor meansto control of the main thermostat.

18. In a control system for heating devices including burner means, a main thermostat responsive to the temperature produced by said burner means, a valve for causing; modulation said electrical motor means being controlled by said main thermostat, and time-delay thermo-' static means operated from an initial to a second position in response to temperature changes produced by the burner means at rates above a predetermined value, and operated back to initial position upon'reduction of rate of temperature change to below said value, said timedelay means being connected to cause a tem- 'porary cessation of the operation of said elecjacent said main thermostat varies beyond a predetermined amount.

19. In a control system for heating devices including burner means, a main thermostat responsive to the temperature from said burner connecting said motors with said auxiliary valve,

said electrical motor means being controlled by said main thermostat, and time-delay, thermostatic means operated from an initial toa second position in response to temperature changes produced by the burner means at rates above a predetermined value, and operated back to initial position upon reduction of rate of temperature change to below said value, said time-delay means being connected to cause a temporary cessation of the operation of said motor means upon rapid change or temperature provided by said burner .means, said valve maintaining its previously achieved position during temporary cessation of. the motor means, and the timedelay thermostatic means being adapted to return to initial position upon reduction of rate of change of said temperature, to return the electrical motor means to control of the main thermostat.

20. In a mechanism of the kind described, a heat-change producing means for effecting heat changes in a space, means for varying the heatchange effect of the heat-change producing means, a first control operable into open and closed positions in response to the temperature condition of the space, and a second control operable in response to changes in temperature occurring at rates above a predetermined value, to move from a closed to an open position, and operable upon failure of temperature to change at such rates, to a closed position, said second control being disposed to be responsive to rate of change of temperature produced by the heatchange producing means, and means connecting both controls with the varying means to produce operation thereof only when both are closed,-

whereby upon demand for heat change at the first control, the heat-change producing device may operate intermittently.

21. In a mechanism of the kind described, means to control the operation of a heat-change producing device to determine the operation thereof to produce heat-changes in a given space, a first thermostatic device in the space operable from open to closed position in accordance with temperature conditions in the space, a second thermostatic device disposed to receive heatchanges produced by the medium as distinguished from those ultimately produced in the space, said second thermostatic device being adapted to operate from closed to open position and back to closed position upon continued sub-' stantial change in one direction, in temperature thereat, but always to operate to closedposition upon cessation of change in temperature thereat, means connecting said first and second thermostatic devices with the heat-change producing device to determine operation thereof only when both are closed, whereby upon demand for heatchange at the first thermostatic device, the heatchange producing device may operate intermittently until the demand is satisfied.

22. In a mechanism of the kind described, means to control the operation of a heat-change producing device to determine the operation thereof to produce heat-changes in a given space, a first thermostatic device in the space operable from open to closed position in accordance with temperature conditions in the space, a second thermostatic device disposed to receive heatchanges produced by the medium as distinguished from those ultimately produced in the space, said second thermostatic device being adapted to operate from closed to open position and back to closed position upon continued substantial change inone direction, in temperature thereat, but always to operate to closed position upon cessation of change in temperature thereat, means connecting said-first and second thermostatic devices with the heat-change producing device to determine operation thereof only when both are closed, whereby upon demand for heat-change at the first thermostatic device, the heat-change producing device may operate intermittently until the demand is satisfied, with means in the second control to adjust the amount of change in temperature required to shift the same from one position to another.

23. In a mechanism of the kind described, a heat-change producing means operable for effecting temperature changes in a space that is subject to reverse changes in temperature when the heat-change producing means is inoperative, means for varying the heat-change effect of the heat-change producing means, a first control operable to open and closed positions in response to the temperature condition of the space, a second control operable in response to changes in temperature in either direction, above a predetermined value, to move from a first position to a second position, and operable upon failure oftemperature to change at such rates, to a closed position, said second control being dis-' posed to be responsive to rate of change in temperature produced by operation or cessation of the heat-change producing means, means connecting both controls with the varying means to determine operation thereof only when the first control is closed and the second is in its first position, whereby upon demand for heat change at the first control, the heat-change producing means may operate intermittently, means to adjust the second control to obtain variations in amount of change in temperature required to effect operation of said second control, said adjusting means including mechanism to produce a different amount of change required to operate from first to second position than from second to first.

24. In a control system for controlling the temperature of a desired place, a heat-change producing means, means conducting an ingredient to the heat-change producing means to cause the same to operate and produce heat changes, a main thermostat responsive to the heat changes produced, and located in the space, a control in the ingredient conducting means to cause modulation of the supply thereof to the heat-change producing means, electrical means operable in opposite directions to move the controltoward open and closed positions, said main thermostat controlling said electrical means and control to start the control moving toward open or closed position in accordance with whether the temperature of the place is, above or below a predetermined value, and time-delay thermo- 

